"He had been undergoing some treatment," Furr said. "We can't go into detail on that. I don't know if he was exactly on law enforcement's radar, but it wasn't like there wasn't concern for him. He had not been back to the clinic for over a year, so there's been a time where he was receiving treatment and then stopped."

Cruz, he said, "had been dealing with mental health issues."

One of the public defenders tasked with serving as Cruz's lawyer told reporters, "he's a broken human being. He's a broken child who fell through every single crack."

Cruz was adopted but both of his parents had died, with his mother succumbing to the flu and pneumonia in November. He had been living with a family that allowed him to stay there.

Jim Lewis, an attorney for the family, told CNN it was aware Cruz had an AR-15, which was kept locked up in his bedroom. He also said the family knew he was suffering from depression when he moved in with them in recent months.

"He seemed to be doing better," Lewis said. "He was a smaller kid and [there's] some indication there might have been some bullying going on, but again, he'd been away from the school for over a year and had never shared with them any contempt for the school or anybody here — no anger, just a lot of depression and stuff going on around the loss of his mother."

Peter J. Forcelli is the special agent in charge of the ATF's Miami field division and told The Washington Post that Cruz obtained the AR-15 without issues.

"He purchased the firearm legally," Forcelli said. "No laws were broken in his acquisition of the firearm."

"It cannot be denied that something dangerous and unhealthy is happening in our country," Sessions said. In "every one of these cases, we've had advance indications and perhaps we haven't been effective enough in intervening."

President Donald Trump also pointed to mental illness as a factor in Wednesday's massacre.

So many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behavior. Neighbors and classmates knew he was a big problem. Must always report such instances to authorities, again and again!